Although there have been remarkable advances in the analysis of human chromosome sequences thanks to the progress in human genome research, this does not mean that all the human genetic functions have been clarified. In humans, gene diversity is significantly associated with changes in gene functions. In fact, it is known that in humans, a plurality of mRNAs are transcribed from a particular region of a chromosome to produce different variants.
For the series of genes that have been discovered by the present inventors, and that can be used as biomarkers specific for cancer (abbreviated as “cancer-specific genes” or “cancer-specific genes 1 to 8” as required), known variants have been reported. Examples of such known variants include known variants of cancer-specific gene 1 (Genbank accession number: NM—006894.4; non-patent documents 1 and 2), cancer-specific gene 2 (Genbank accession number: NM—000966.3; non-patent documents 3 and 4), cancer-specific gene 3 (Genbank accession number: NM—016559.1; non-patent documents 5 and 6), cancer-specific gene 4 (Genbank accession number: NM—004114.2; non-patent documents 7 and 8), cancer-specific gene 5 (Genbank accession number: NM—005476.3; non-patent documents 9 and 10), cancer-specific gene 6 (Genbank accession number: NM—004849.1; non-patent documents 11 and 12), cancer-specific gene 7 (Genbank accession number: NM—022777.1), cancer-specific gene 8 (Genbank accession number: NM—005122.2; non-patent document 13 and 14).
However, it is not known that the cancer-specific genes 1 to 8 can be useful as biomarkers specific for cancer, and that the particular variants discovered by the present inventors exist in the cancer-specific genes 1 to 8.    Non-patent document 1: Lomri, N. et al., Proc. Natl. Acad. Sci. U.S.A. 89 (5), 1685-1689 (1992)    Non-patent document 2: Lomri, N. et al., Proc. Natl. Acad. Sci. U.S.A. 92 (21), 9910 (1995)    Non-patent document 3: Krust, A. et al., Proc. Natl. Acad. Sci. U.S.A. 86 (14), 5310-5314 (1989)    Non-patent document 4: Ishikawa, T. et al., Mol. Endocrinol. 4 (6), 837-844 (1990)    Non-patent document 5: Amery, L. et al., Biochem. J. 357 (PT 3), 635-646 (2001)    Non-patent document 6: Wang, X. et al., J. Biol. Chem. 279 (44), 45855-45864 (2004)    Non-patent document 7: Smallwood, P. M. et al., Proc. Natl. Acad. Sci. U.S.A. 93 (18), 9850-9857 (1996)    Non-patent document 8: Gecz, J. et al., Hum. Genet. 104 (1), 56-63 (1999)    Non-patent document 9: Mitrani-Rosenbaum, S. et al., Hum. Mol. Genet. 5 (1), 159-163 (1996)    Non-patent document 10: Salama, I. et al., Biochem. Biophys. Res. Commun. 328 (1), 221-226 (2005)    Non-patent document 11: Hammond, E. M. et al., FEBS Lett. 425 (3), 391-395 (1998)    Non-patent document 12: Baumann, P. et al. Science 292 (5519), 1171-1175 (2001)    Non-patent document 13: Baes, M. et al., Mol. Cell. Biol. 14 (3), 1544-1552 (1994)    Non-patent document 14: Masuno, M. et al., Genomics 20 (1), 141-142 (1994)